Real-time traffic data applications in the Mobility Lab of Helsinki - Case Smart Junction

City of Helsinki is developing itself as a platform named Jätkäsaari Mobility Lab for testing and enabling innovative solutions for smooth, safe and sustainable mobility. In this paper, we describe how one of the main pilot case, a project titled Smart Junction, and the new sensor installations are used in specific research and development projects while also enabling third party development through real-time open data and APIs. Within the Smart Junction project, the focus is on combining the various data sources into one coherent picture of the traffic situation called real-time digital twin. The main benefit of the digital twin is that any service or application that needs access to traffic situation data, can get it directly from the digital twin without any prior knowledge of the sensors and their configurations. The main use case in Jätkäsaari is the introduction of new signal control strategies based on the real-time digital twin.